The Pediatric Oncology Division at Emory University is the only pediatric cancer center within 180-mile radius, and offers multimodal therapy to children with malignant diseases. Although this division was inactive for a period of one year, it is currently very active and caring for approximately 100 children with malignant disorders. This division is unique in that it cares for private patients at Emory University Clinic and The Henrietta Egleston Hospital for Children and for indigent patients at Grady Memorial Hospital. This division cares for children in the Atlanta area (population 1.7 million), the State of Georgia, and other neighboring states (North Carolina, South Carolina, and Alabama). At the time of diagnosis of a malignant disease in a child, the clinical findings are reviewed and management is discussed at the Pediatric Tumor Conference by attending pediatric oncologists, radiation therapists, surgeons and pathologists, in order to assure that each child receives optimal therapy. In collaboration with the Southwest Oncology Group, the center offers access to new intensive therapeutic regimes and experimental agents to approximately 100 children with malignant diseases. Extensive ancillary studies, both at the clinical and preclinical level, are underway in parallel with the oncology studies in children. Thus, the bone marrow culture technics for the growth of granulopoietic and erythroid progenitor cells are being used to evaluate the effects of chemotherapeutic agents on granulopoiesis and erythrpoiesis in man. The same technic is being employed to investigate the cryopreservation of human bone marrow cells. In addition, subcutaneously implanted mouse melanoma is used as an animal model to evaluate response of solid tumors to chemotherapy. A quantitative clonogenic assay system has been developed to determine parameters of cell killing by antitumor agents. In addition, the effect of drugs on bone marrow granulocytic progenitor cells (CFC) will be determined in culture.